Multilayer thin film drug delivery device and methods of making and using the same

ABSTRACT

Multilayer thin film devices that include a bioactive agent for elution to the surrounding tissue upon administration to a subject are provided. The multilayer thin film devices are useful as medical devices, such as ocular devices. Also provided are methods and kits for localized delivery of a bioactive agent to a tissue of a subject, and methods of preparing the subject devices. The multilayer thin film medical device includes a first layer, a bioactive agent and a second layer. The first and the second layers may be porous or non-porous. The devices have a furled structure, suitable for administration to a subject.

CROSS-REFERENCE TO EARLIER FILED APPLICATION

This application is a Continuation of U.S. patent application Ser. No.14/110,549, filed Dec. 19, 2013, which application is a 371 ofPCT/US12/33366 filed Apr. 14, 2011 which claims priority to U.S.Provisional Patent Application Ser. No. 61/475,373, filed Apr. 14, 2011,which is incorporated herein by reference in its entirety.

BACKGROUND

Chronic diseases often require long-term treatment strategies that relyon conventional drug delivery methods such as injections and otherprocedures that necessitate regular hospital or office visits.Controlled long-term drug delivery has many advantages over thesetraditional methods. Maintaining drug concentration within a clinicallyrelevant therapeutic window minimizes overdosing and drug waste andleads to fewer side effects and an increase in patient compliance anddrug efficacy. Several technologies have been developed that utilizethese principles of long-term drug delivery, including implantableinfusion pumps for the delivery of chemotherapeutics, insulin pumps forthe treatment of diabetes mellitus, and spinal drug administrationsystems for the treatment of lower back pain.

Recent developments in long-term drug delivery systems have includedminiaturization to target specific organs. For example, the eye is ofinterest for long-term controlled drug delivery due to its small sizeand the chronic nature of many of the diseases that affect it includinguveitis, diabetic retinopathy, macular edema, glaucoma, and age-relatedmacular degeneration (AMD).

Protein therapeutics are an effective treatment for many diseases. Forexample, neovascular AMD is effectively treated with anti-vascularendothelial growth factor (VEGF) formulations such as ranibizumab(Lucentis, Genentech, Inc.) and bevacizumab (Avastin, Genentech, Inc.).These treatments are injected directly into the vitreous cavity on amonthly basis, an invasive procedure whose side effects can includeendophthalmitis, intraocular pressure elevation, cataract, and retinaldetachment. For AMD specifically, the poor biostability of anti-VEGFdrugs and other large protein and antibody-based agents constrainslong-term drug delivery. With a half-life of several days, theseanti-VEGF drugs clear from the eye after standard intravitrealinjection, necessitating monthly super-threshold bolus doses in attemptto prolong therapeutically effective periods.

A sustained and controlled release drug delivery device capable ofdelivering drugs including protein therapeutics to the anterior and/orposterior segments of the eye while minimizing the number of intraocularinjections required for treatment and maintaining a therapeuticconcentration of drug within the eye is of interest.

SUMMARY

Multilayer thin film medical devices that include a bioactive agent forelution to the surrounding tissue upon administration to a subject areprovided. Also provided are methods and kits for localized delivery of abioactive agent to a tissue of a subject, and methods of preparing thesubject devices. The multilayer thin film medical device includes afirst layer, a bioactive agent and a second layer. The first and thesecond layers may be porous or non-porous. The devices have a furledstructure, suitable for administration to a subject via needle or acatheter.

Multilayer thin film devices that include a bioactive agent for elutionto the surrounding tissue upon administration to a subject are provided.The devices are useful as medical devices for drug delivery, includingocular devices for delivery of bioactive proteins and small molecules.Also provided are methods of localized delivery of a bioactive agent toa tissue of a subject, and methods of preparing the subject multilayerthin film medical devices.

In certain embodiments, the multilayer thin film medical devices includea first thin film layer, bioactive agent and a second thin film layer,where the bioactive agent is positioned between the first and secondlayers. The first layer may include a polymer and a pore forming agent.The second layer may be porous or non-porous. The first and secondlayers may be biodegradable or non-biodegradable. Followingadministration to a subject, the pore forming agent dissolves to producea porous first layer and provides for elution of the bioactive agent(e.g., a protein therapeutic) to the surrounding tissue. In someembodiments, the device further includes a third nanostructured porouslayer positioned between the first layer and the reservoir of bioactiveagent.

In certain embodiments, the multilayer thin film medical devices includea first non-porous thin film layer, a bioactive agent, and a secondnon-porous thin film layer, where the bioactive agent is positioned inbetween the first and second layers.

In certain embodiments, the device has a furled structure, where thestructure unfurls in vivo in the presence of a hydrating liquid. Incertain cases, the device having a furled structure may be administeredto a subject by injection into a target tissue.

These devices and methods find use in a variety of applications in whichdelivery of bioactive agents to subjects is desired.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments described in this disclosure are best understood fromthe following detailed description when read in conjunction with theaccompanying drawings. It is emphasized that, according to commonpractice, the various features of the drawings are not to-scale. On thecontrary, the dimensions of the various features are arbitrarilyexpanded or reduced for clarity. Included in the drawings are thefollowing figures:

FIGS. 1A-F show scanning electron micrograph (SEM) images andcorresponding pore size histograms of polycaprolactone (PCL)/gelatinthin films after five days incubation in PBS.

FIGS. 2A-B show graphs of the porosity and mass loss of PCL/gelatin thinfilms after incubation in PBS.

FIGS. 3A-C illustrate the fabrication of a multilayer thin film device.(A) Fabrication; (B) a finished device of ˜2 mm in diameter; and (C)profile of the device edge.

FIGS. 4A-B show the fractional elution profile of proteins ((A) BSA; (B)IgG) from PCL/gelatin and PCL-only thin film devices.

FIG. 5 shows a comparison of the rates of elution of BSA and IgG from aPCL/gelatin thin film device.

FIG. 6A illustrates that the bioactivity of IgG eluted from aPCL/gelatin thin film device is maintained over time, as determined byELISA and BCA assays. FIG. 6B illustrates in vivo activity of IgG elutedfrom PCL/gelatin thin film device 6 weeks-post administration.

FIGS. 7A-C show a furled thin film device (A), and an unfurled device(B), that has a thin form factor (C).

FIGS. 8A-E illustrate thin film fabrication procedure. FIGS. 8F-G showscanning electron microscope (SEM) images of a typical nanostructuredPCL film.

FIGS. 9A-C show a schematic of an exemplary multilayer thin film device(A) and side-profile SEM images of microporous (B) and nanoporous thinfilm layers (C). FIGS. 9 D-G depict additional configurations ofexemplary multilayer thin film devices. FIG. 9D shows a schematic of amultilayer thin film device which includes a centrally located layerincluding a reservoir in which a bioactive agent is present. Thebioactive agent in the reservoir can elute via the nanoporous thin filmlayers sandwiching the reservoir containing layer. Each of thenanoporous layers are covered by a microporous layer. FIG. 9E provides aschematic of a multilayer thin film device which includes a centrallayer comprising reservoirs in which two different bioactive agents arepresent. The bioactive agents in the reservoirs can elute via thenanoporous thin film layers sandwiching the reservoirs containing layer.Each of the nanoporous layers are covered by a microporous layer. FIG.9F illustrates a multilayer thin film device similar to the one depictedin FIG. 9A with the addition of another reservoir containing thebioactive agent. The two reservoirs include different bioactive reagents(FIG. 9G).

FIG. 10A shows wells in a non-porous PCL thin film that are filled withFITC-IgG protein. FIG. 10B shows the dimensions of an exemplarymultilayer thin film device.

FIGS. 11A-11C depict exemplary apparatus usable for fabricatingmultilayer thin films disclosed herein.

FIG. 12 shows release of protein from a multilayer thin film device asdisclosed herein.

FIG. 13 illustrates the release kinetics of a small molecule (Rapamycin,molecular weight 914.172 Da) from a nanoporous thin film device (solidcircles), non-porous device (solid squares) and from a PCL thin filmwith drug mixed in the polymer film (solid triangles). The nanoporousthin film device consisted of a supported nanostructured film(nanostructured pores of 20-40 nm and support layer pores of 1-3microns). The non-porous film contained Rapamycin in a centralreservoir. For PCL thin film, the small molecule is mixed within thepolymer itself rather than contained in a reservoir.

DETAILED DESCRIPTION

As summarized above, multilayer thin films that include a bioactiveagent for elution to the surrounding tissue upon administration to asubject are provided. The subject devices include a first layer, abioactive agent and a second layer, where the bioactive agent ispositioned between the first and second layers. One or more bioactiveagents may be included between the first layer and the second layer. Thefirst and second layers may be non-porous. The first layer may include abiodegradable polymer and a pore forming agent. Following administrationto a subject, the pore forming agent dissolves to produce a porous firstlayer and provides for elution of the bioactive agent (e.g., a proteintherapeutic) to the surrounding tissue. In the absence of a pore formingagent the first layer may be non-porous. The second layer may benon-porous or porous. In some embodiments, any or all layers may benon-biodegradable. In other embodiments, the first layer and/or secondlayer may be biodegradable.

In some embodiments, the device further includes a third nanostructuredporous layer positioned between the first layer and the bioactive agent.In certain embodiments, the subject device has a furled structure. Thefurled structure is suitable for administration of the device to asubject by injection or via a catheter. Once placed into a subject, thestructure unfurls in vivo in the presence of a hydrating liquid, whichhydrating liquid may be a body fluid of the subject. In someembodiments, the device contains two non-porous films, which are eitherbiodegradable or non-biodegradable with the bioactive agent positionedbetween these films.

The subject devices contain a reservoir of the bioactive agent for localdelivery to the surrounding tissue after placement of the device in asubject. In some embodiments, the bioactive agent is eluted from thedevice over an extended period of time. Moreover, the release or elutionof the drugs or biological agents from the subject devices can becontrolled by parameters, such as but not limited to, the size,porosity, thickness, and composition of the thin film layers. Therelease kinetics of specific drugs is controlled to achieve sustainedand substantially constant release of the drug over an extended periodof time. Exemplary medical devices for the subject device include, butare not limited to, a cardiovascular device, a neurological device, aneurovascular device, a gastrointestinal device, a muscular device, anocular device, and the like. In some embodiments, the multilayer thinfilm can be used for localized delivery of the bioactive agent to a softtissue, such as joint space, nerve, liver, kidney, gastrointestinaltract, pancreas, prostate, colon, and the like.

In some embodiments, the device contains more than one reservoirpositioned between the first and second film layer, where each reservoircontains a single bioactive agent or two or more different bioactiveagents. The subject device may be injected into a target tissue, orsurgically implanted in a target tissue, or administered orally. Beforecertain embodiments are described in greater detail, it is to beunderstood that this disclosure is not limited to the certainembodiments described, as such may, of course, vary. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting, since the scope of the disclosure will be limited only by theappended claims.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimits of that range is also specifically disclosed. Each smaller rangebetween any stated value or intervening value in a stated range and anyother stated or intervening value in that stated range is encompassedwithin the disclosure. The upper and lower limits of these smallerranges may independently be included or excluded in the range, and eachrange where either, neither or both limits are included in the smallerranges is also encompassed within the disclosure, subject to anyspecifically excluded limit in the stated range. Where the stated rangeincludes one or both of the limits, ranges excluding either or both ofthose included limits are also included in the disclosure.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this disclosure belongs. Although any methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of the embodiments described herein, somepotential and preferred methods and materials are now described. Allpublications mentioned herein are incorporated herein by reference todisclose and describe the methods and/or materials in connection withwhich the publications are cited. It is understood that the presentdisclosure supersedes any disclosure of an incorporated publication tothe extent there is a contradiction.

It must be noted that as used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include plural referents unless thecontext clearly dictates otherwise. Thus, for example, reference to “acell” includes a plurality of such cells and reference to “the compound”includes reference to one or more compounds and equivalents thereofknown to those skilled in the art, and so forth.

The publications discussed herein are provided solely for theirdisclosure prior to the filing date of the present application. Nothingherein is to be construed as an admission that the present disclosure isnot entitled to antedate such publication by virtue of prior invention.Further, the dates of publication provided may be different from theactual publication dates which may need to be independently confirmed.

Multilayer Thin Films

Multilayer thin film medical devices that include a plurality of thinfilm layers and a bioactive agent for use in the local delivery of thebioactive agent to a tissue of a subject in need thereof are provided.In some embodiments, at least one thin film, such as 1, 2, 3, 4, 5 ormore thin films, of the subject device includes a biodegradable ornon-degradable polymer and a pore forming agent. In some embodiments, atleast one thin film, such as 1, 2, 3, 4, 5 or more thin films, of thesubject device is a porous thin film (e.g., a microporous thin film or ananoporous thin film). In some embodiments, the plurality of thin filmlayers are non-porous and include a bioactive agent between twonon-porous thin film layers.

In some embodiments, a multilayer thin film medical device includes afirst layer including a biodegradable or non-degradable polymer and apore forming agent, a bioactive agent, and a second layer in contactwith the bioactive agent, where the bioactive agent is positionedbetween the first layer and the second layer.

In some embodiments, the second layer is a non-porous layer (e.g., abacking layer). In some embodiments, the second layer is a porous layer(e.g., a microporous or nanoporous layer). The second layer may includea biodegradable or non-degradable polymer and a pore forming agent. Incertain embodiments, the second layer is a nanostructured porous layer.

In some embodiments, the multilayer thin film medical device includes abioactive agent that is positioned between two porous layers. In somecases, one or both of the layers is a nanostructured porous layer. Insome cases, one or both of the layers is a microporous layer. In someembodiments, the multilayer thin film medical device includes areservoir of a bioactive agent that is positioned between two layers,where one or both of the layers includes a biodegradable ornon-degradable polymer and a pore forming agent. In certain embodiments,the subject device further includes one or more additionalnanostructured porous layers positioned between the first and/or secondlayer and the reservoir of the bioactive agent.

In some embodiments, a multilayer thin film medical device includes afirst layer including a biodegradable or non-degradable polymer and apore forming agent, a bioactive agent, and a second non-porous layer incontact with the bioactive agent, where the bioactive agent ispositioned between the first layer and the second layer.

In some embodiments, a multilayer thin film medical device includes afirst porous layer including a biodegradable or non-degradable polymer,a bioactive agent, and a second non-porous layer in contact with thebioactive agent, where the bioactive agent is positioned between thefirst layer and the second layer.

In certain embodiments, the subject device includes a furled structure(e.g. a substantially cylindrical, substantially conical, orsubstantially frusto-conical structure). In certain embodiments, thesubject device includes an unfurled structure, where the structure mayhave a substantially circular peripheral edge.

In certain embodiments, the subject device further includes a thirdnanostructured porous layer positioned between the first layer and thereservoir of the bioactive agent.

In some embodiments, a multilayer thin film medical device includes afirst non-porous layer including a biodegradable or non-degradablepolymer, a bioactive agent, and a second non-porous layer in contactwith the bioactive agent, where the bioactive agent is positionedbetween the first layer and the second layer.

In certain embodiments, in the subject devices, the first non-porouslayer and the second non-porous layer are in contact with each other atthe edges of the multilayer thin film thereby sealing the bioactive druginside the multilayer thin film. In certain embodiments, either or bothof the non-porous layers are biodegradable. In other embodiments, theeither or both of the non-porous layers are non-biodegradable.

In certain embodiments, in the subject devices, the bioactive agent ispresent as a thin pellet of lyophilized material. In certainembodiments, in the subject devices, the bioactive agent is deposited ina plurality of reservoirs are located across one surface of the secondnon-porous layer. In other embodiments, two or more bioactive agents aredeposited in the plurality of reservoirs, for example, in the samereservoir or in different reservoirs.

In certain embodiments, a first bioactive agent is deposited in a firstreservoir of the plurality of reservoirs located across one surface ofthe second non-porous layer and a second bioactive agent is deposited ina second reservoir of the plurality of reservoirs.

In other embodiments, a plurality of bioactive agents is present in themultilayer thin film device. For example, two or more bioactive agentsmay be present in between a first thin film layer and a second thin filmlayer.

Pore Forming Agents

The pore forming agent is capable of dissolving or eroding away from thefirst thin film layer to produce a porous first thin film of the polymerthat remains. Application of suitable conditions, e.g., contact with anaqueous liquid in vivo, will dissolve the pore forming agent. Exemplaryconditions are set forth below. For example, upon placement of thedevice in the eye of a subject, the pore forming agent is contacted withvitreous fluid and dissolves away thereby providing release over time ofthe bioactive agent through the pores that are formed in the thin film.In certain embodiments, the dissolution of the pore forming agent israpid, e.g., elution of the bioactive agent begins within about 60minutes after administration, such as within about 30 minutes, withinabout 15 minutes, within about 10 minutes, within about 5 minutes, orwithin about 2 minutes after administration.

In some embodiments, the porous thin film that is formed afterdissolution of the pore forming agent is microporous, e.g., the thinfilm comprises a porous structure having pore sizes of about 1 μm toabout 100 μm, such as about 1 μm to about 30 μm, about 1 μm to about 20μm, or about 1 μm to about 10 μm. In certain embodiments, the porousthin film has an average pore size of between about 1 μm and about 30μm, such as between about 1 μm and about 15 μm, between about 1 μm andabout 10 μm, or between about 1 μm and about 5 μm. In certainembodiments, the porous thin film has a % porosity of between about 20%and about 0.01%, such as between about 10% and about 0.1%, between about5% and about 0.1%, or between about 2% and about 0.1%, and includingbetween about 0.1% and about 0.4%, between about 0.4% and about 1%, andbetween about 1% and about 2%. In certain embodiments, the microporousthin film has % porosity of 0.1%, 0.5% or 1.8%.

In some cases, the pore forming agent is biocompatible and/orbiodegradable, and capable of dissolution upon administration to asubject. A suitable pore forming agent may be selected in view of thespecific bioactive agent and composition of the thin films, and thedesired elution profile or release rate. Any suitable water solublepolymer or hydrogel may be used as a pore forming agent. The poreforming agent may be a naturally occurring agent or polymer or asynthetic agent or polymer. In some embodiments, the pore forming agentis a water soluble polymer such as a polyethylene glycol, apolyoxyethylene copolymer, an acrylate polymer, an acrylate-acrylic acidcopolymer, a polyacrylic acid, an acrylate copolymer includingquaternary ammonium groups, a polyacrylamide, a polyvinyl alcohol,hyaluronan, or a polyvinylpyrrolidone. In some embodiments, the poreforming agent is a carbohydrate, a protein or protein derivative, or thelike. Exemplary pore forming reagents include, but are not limited to,gelatin, a polyethylene glycol (PEG), chitosan, polyvinylpyrrolidone(PVP), polyvinyl alcohol, or agarose. Any suitable PEG may be selectedas a pore forming agent.

In certain embodiments, at least one thin film of the subject devicesincludes a ratio by mass of biodegradable or non-biodegradable polymerto pore forming agent that is in the range of between about 1:2 and99:1, such as between about 1:2, 1:5, or about 7:3 and 9:1, such asabout 7:3, about 8:2 or about 9:1.

Biodegradable Polymers

In some embodiments, the subject devices are biodegradable. In someembodiments, the plurality of thin films of the subject devices eachindependently include a biodegradable polymer. In some embodiments, thesecond non-porous thin film layer includes a biodegradable polymer. Insome embodiments, the one or more nanoporous thin film layer includes abiodegradable polymer. Thin films of the subject devices can befabricated from a variety of suitable materials. Exemplary biodegradablepolymers include, but are not limited to, biodegradable or bioerodiblepolymers, such as poly(DL-lactide-co-glycolide) (PLGA),poly(DL-lactide-co-ε-caprolactone) (DLPLCL), poly(ε-caprolactone) (PCL),or combinations or copolymers thereof, as well as natural biodegradablepolymers, such as collagen, and the like. PLGA is a bulk-erodingcopolymer of polylactide (PLA) and polyglycolide (PGA). In someembodiments, the biodegradable polymer includes PLA, PGA, PCL, PLGA, orPLCL.

In some embodiments, the biodegradable polymer includes polycaprolactone(PCL). PCL is an exemplary polymer that is biocompatible andbiodegradable in vivo and well tolerated throughout the duration of thepresence and degradation of the device, [see e.g., Sun et al., “The invivo degradation, absorption and excretion of PCL-based device.”Biomaterials 27(9) (2006) 1735-1740; Beeley et al., “Fabrication,implantation, elution, and retrieval of a steroid-loadedpolycaprolactone subretinal device.” J. Biomed. Mater. Res. A, 73(4)(2005) 437-444; Giavaresi et al.,” New polymers for drug deliverysystems in orthopaedics: in vivo biocompatibility evaluation.Biomedicine & Pharmacotherapy 58(8) (2004) 411-417].

In some cases, under physiological conditions the biodegradable polymerdegrades by random chain scission, which gives rise to a two-phasedegradation. Initially, as molecular weight decreases the physicalstructure is not significantly affected. Degradation takes placethroughout the polymer material, and proceeds until a critical molecularweight is reached, when degradation products become small enough to besolubilized. At this point, the structure starts to become significantlymore porous and hydrated. For example, one combination of fast-resorbingPGA and slow-resorbing PLA allows PLGA copolymers to have a resorptionrate of approximately 6 weeks.

In some cases, the biodegradable polymer has a MW of about 80 kDa ormore and does not degrade until after 1 year or more in the tissue of asubject. In some embodiments, the macroscopic degradation of abiodegradable polymer (e.g., PCL) may occur at about 8 kDa. In someembodiments, the MW of the biodegradable polymer is selected so as totune the degradation time of the material in vivo. For example, a PCLpolymer of about 15 to about 20 kDa may start to structurally break downafter 4 months and lose mechanical integrity by 6 months.

In some embodiments, the biodegradable polymer includes a polymer havinga MW of about 10 kDa or more, such as about 15 kDa or more, about 20 kDaor more, about 30 kDa or more, about 40 kDa or more, about 50 kDa ormore, about 60 kDa or more, about 70 kDa or more, about 80 kDa or more,about 90 kDa or more, or about 100 kDa or more. In some embodiments, thebiodegradable polymer includes a blend of polymers where the polymersmay be of the same or a different type of polymer, and each polymer maybe of a different MW. In some embodiments, the biodegradable polymerincludes a blend of a high MW polymer and a low MW polymer. The high MWpolymer may be of about 25 kDa or more, such as about 30 kDa or more,about 40 kDa or more, about 50 kDa or more, about 60 kDa or more, about70 kDa or more, about 80 kDa or more, about 90 kDa or more, or about 100kDa or more. The low MW polymer may be of about 20 kDa or less, such asabout 15 kDa or less, about 10 kDa or less, about 8 kDa or less, about 6kDa or less, or about 4 kDa or less.

In some embodiments, the ratio by mass of the high MW polymer to the lowMW polymer in a blend of polymers is between about 1:9 and about 9:1,such as between about 2:8 and about 8:2, between about 2:8 and about6:4, or between about 2:8 and about 1:1. In certain embodiments, theratio by mass of the high MW polymer to the low MW polymer is about3:17, about 2:8, about 1:3, about 3:7, about 7:13, about 2:3, about9:11, about 1:1, about 11:9, or about 3:2. In some embodiments, thecomposition of the biodegradable polymer is selected to provide amelting temperature (T_(m)) of between about 50° C. and about 70° C.,such as between about 58° C. and about 63° C. In some embodiments, thecomposition of the biodegradable polymer is selected to provide a glasstransition (T_(g)) of between about −50° C. and about −80° C., such asbetween about −60° C. to about −65° C.

In some embodiments, the thickness of the biodegradable polymer layermay range from about 1 micron to about 100 microns. In some embodiments,the thickness of the biodegradable polymer layer may range from about100 nm to about 990 nm. For example, the thickness of the biodegradablepolymer layer may be about 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600nm, 700 nm, 800 nm, 900 nm, or 990 nm.

Reservoir of Bioactive Agent

The subject devices include a reservoir of one or more biologicalagents. The reservoir is contained within the subject device, such thatupon administration, the bioactive agent is subsequently eluted from thedevice into the surrounding tissue of the subject through one or moreporous thin film layer.

In some embodiments, the subject device utilizes a bioactive agent in adry lyophilized form, packaged within the device and subsequentlyresolubilized in situ for release into the surrounding tissue followingadministration. For example, after insertion into the eye, lyophilizedbioactive agent is sequestered within the device, restricted from theocular environment within the reservoir, maintaining bio-activity formonths, where rehydration and release are controlled via engineeredpores (e.g., in a nanoporous thin film and/or a microporous thin film).In such embodiments, the stability and bioactivity of bioactive agent inthe reservoir is maintained for an extended period of time afteradministration.

In some embodiments, the reservoir is defined by a continuous layer of acomposition that includes the bioactive agent. For example, a layer oflyophilized material as depicted in FIG. 3. In such embodiments, thereservoir of bioactive agent is positioned between a first thin filmlayer, and a second thin film (e.g., a non-porous thin film), where thefirst layer may be a thin film that includes a biodegradable ornon-biodegradable polymer and a pore forming agent, or a microporousthin film from which the pore forming agent has dissolved. In certainembodiments, a third nanoporous thin film layer is positioned betweenthe first layer and the reservoir of bioactive agent.

In some embodiments, the reservoir is defined by a plurality ofstructures in a thin film layer, such as but not limited to, wells,pores, chambers or channels located through and/or across a surface ofthe thin film, where the structural voids are filled with a compositionthat includes the bioactive agent. For example, the reservoir may bedefined by a plurality of wells in a non-porous thin film that arefilled with bioactive agent, as depicted in FIG. 10. In suchembodiments, the reservoir defined by the plurality of structures may becovered with a further thin film that provides a porous layer uponadministration through which the bioactive agent can diffuse (e.g., ananoporous thin film, a microporous thin film or precursor thereof, or acombination thereof). In such cases, this reservoir defined by theplurality of structures may be described as being positioned between afirst thin film layer and a second thin film layer. In some cases, thereservoirs may include a plurality of bioactive agents. In someembodiments, a first reservoir of the plurality of reservoirs mayinclude a first bioactive agent, a second reservoir of the plurality ofreservoirs may include a second bioactive agent. In some embodiments, aplurality of different bioactive agents may be present in the differentreservoirs. In some embodiments, the reservoir is defined by multiplethin film layers (e.g., multiple layers of about 10 μm or less inthickness) where each layer may sequester bioactive drug, and where eachlayer may be protected from exposure to a hydrating liquid (e.g., liquidfrom the surrounding tissues of a subject) by the layer above it. Insuch cases, after administration, bioactive drug is eluted successivelyfrom each layer of the reservoir over an extended period of time. Eachlayer of the reservoir may further comprise a biodegradable polymer thatincludes structures, such as nanostructures of pores, channels or wells.

The pore forming agent may protect the bioactive agent from degradationby sealing and maintaining the bioactive agent in the device in alyophilized state. In certain embodiments, the device is storage stable,e.g., the bioactive agent is a protein therapeutic that maintains itsbioactivity for an extended period of time, such as, 1 or more months, 2or more, 3 or more, 6 or more, 9 or more or 12 or more months. In someembodiments, dissolution of the pore forming agent provides for anelution profile of the bioactive agent to the surrounding tissue uponplacement of the device in a subject (e.g., a delayed elution profile,two elution profiles, a substantially zero order elution profile).

Exemplary bioactive agent include, but are not limited to, polypeptides,nucleic acids, such as DNA, RNA, and siRNA, growth factors, steroidagents, antibody therapies, antimicrobial agents, antibiotics,antiretroviral drugs, anti-inflammatory compounds, antitumor agents,anti-angiogeneic agents, and chemotherapeutic agents. In certainembodiments, the multilayer thin film includes a covalently attachedbioactive agent. In some embodiments, the multilayer thin film devicefurther includes cells, such as stem cells, pancreatic islets or betacells, retinal progenitor cells, cardiac progenitor cells,osteoprogenitor cells, neuronal progenitor cells, and the like.

Any convenient bioactive agent may be selected for use in the subjectdevices. In some embodiments, the bioactive agent is a small molecule ora large molecule, such as a protein (e.g., a protein biologic or anantibody) or an aptamer (e.g., a single stranded polynucleotide drug).In certain cases, the bioactive agent may be combined with apharmaceutically acceptable additive before or after placement of thebioactive agent on a layer of the subject device. The term“pharmaceutically acceptable additive” refers to preservatives,antioxidants, emulsifiers, dyes and excipients known or used in thefield of drug formulation and that do not unduly interfere with theeffectiveness of the biological activity of the active agent, and thatis sufficiently non-toxic to the patient. For example, the bioactiveagent may be formulated with inert fillers, anti-irritants, gellingagents, stabilizers, surfactant, emollients, coloring agents,preservatives, or buffering agents, as are known in the art. The term“excipients” is conventionally known to mean carriers, diluents and/orvehicles used in formulating drug compositions effective for the desireduse.

In some embodiments, the bioactive agent is a small molecule, such asbut not limited to, an anti-glaucoma drug, an anti-inflammatory drug, animmunosuppressant drug, a vitamin, micronutrient or antioxidant, anantibacterial drug (e.g., vancomycin or cephazolin), an anti-viral drug(e.g., gancyclovir, acyclovir or foscarnet), an anti-fungal drug (e.g.,amphotericin B, fluconazole or voriconazole) or an anti-cancer drug(e.g., cyclophosphamide or melphalan). In certain embodiments, the smallmolecule is a vitamin, micronutrient or antioxidant, such as but notlimited to, vitamin A, vitamin C, vitamin E, zinc, copper, lutein orzeaxanthin. In certain embodiments, the small molecule is animmunosuppressant drug, such as but not limited to, cyclosporine,methotrexate or azathioprine. In certain embodiments, the small moleculeis an anti-inflammatory drug, such as but not limited to, acorticosteroid (e.g., triamcinolone acetonide or dexamethasone) or anon-steroidal drug (e.g., ketorolac or diclofenac). In certainembodiments, the small molecule drug is an anti-glaucoma drug, such asbut not limited to, latanaprost, travarost, timolol, brimonidine ordorzolamide.

In certain embodiments, the small molecule may be a hydrophobic smallmolecule. In other embodiments, the small molecule may be a hydrophilicsmall molecule. In general, small molecules do not include proteins.

In some embodiments, the bioactive agent is a large molecule drug thatis an anti-angiogenic drug, an anti-VEGF drug, an immunosuppressantdrug, a complement inhibitor, a neuromuscular blocker drug, ahematopoietic factor (e.g., erythropoietin), a thrombolytic drug (e.g.,tissue plasminogen activator) or a collagenolytic drug (e.g.,hyaluronidase or microplasmin). In certain embodiments, the largemolecule drug is an immunosuppressant drug, such as but not limited to,etanercept, infliximab or daclizumab. In certain embodiments, the largemolecule drug is a neuromuscular blocker drug, such as but not limitedto, botulinum toxin A. In certain embodiments, the large molecule drugis a complement inhibitor, such as but not limited to, an anti-C3compound.

In some embodiments, the bioactive agent is a protein, such as but notlimited to, an antibody therapeutic, such as ranibizumab (Lucentis©,Genentech, Inc.), bevacizumab (Avastin®, Genentech/Roche), trastuzumab(Herceptin®, Genentech, Inc.), rituximab (Rituxan®, Genentech, Inc.),gentuzumab ozogamicin (Myllotarg®, Pfizer, Inc.) or cetuximab (Erbitux®,ImClone LLC); an enzyme such as but not limited to, a collagenase, apeptidase, or an oxidase; a protein therapeutic, such as but not limitedto, insulin, erythropoietin (e.g., rHuEPO-alpha, Epoetin alfa), a bloodfactor, an interferon (e.g., interferon alfa-2b (INTRON® A) orpeginterferon alfa-2b). In certain embodiments, the bioactive agent is aprotein that modulates the activity of a therapeutic target, such as butnot limited to, VEGF, GP120, RANKL, NGF or TNF-alpha. In certainembodiments, the bioactive agent is a large molecule drug that is ananti-angiogenic drug (e.g., a PDGF inhibitor or an anti-VEGF drug). Incertain embodiments, the bioactive agent is a VEGF antagonist, such asbut not limited to ranibizumab or bevacizumab.

In some embodiments, the bioactive agent is a protein therapeutic, suchas but not limited to ranibizumab, bevacizumab, trastuzumab, rituximab,gentuzumab ozogamicin or cetuximab.

The bioactive agents may be in a purified form, partially purified form,recombinant form, or any other form appropriate for inclusion in themultilayer thin film medical device. The agents may be free ofimpurities and contaminants. The bioactive agent(s) disposed in themultilayer thin film medical device may be include stabilizing agents asadditives to increase the stability of the bioactive agent(s). Forexample, the bioactive agent may be combined with a stabilizer, such ascommercially available stabilizers. In general, the stabilizer used maydepend upon the type of bioactive agent(s) included in the multilayerthin film device.

Nanoporous Thin Films

In some embodiments, one or more thin film layers, such as 1, 2, 3 ormore thin films, of the subject devices are nanoporous. As used herein,the term “nanoporous” refers to a nanostructured thin film porous layerwhere the average pore size is sub-micrometer, such as between about 1nm and about 990 nm, between about 1 nm and about 100 nm, between about2 nm and about 700 nm, between about 2 nm and about 500 nm, betweenabout 3 nm and about 400 nm, between about 5 nm and about 200 nm, orbetween about 7 nm and about 50 nm.

In some embodiments, a nanoporous thin film is positioned betweenanother thin film as described above (e.g., that includes abiodegradable polymer and a pore forming agent), and a reservoir ofbioactive agent. The nanoporous thin film is in contact with thebioactive agent and provides for a desired elution profile of thebioactive agent (e.g., a substantially zero-order elution profile thatavoids an initial burst effect) from the subject device. For example, bycontrolling parameters of the nanoporous thin film such as pore size,polymer thickness, porous area, and pore density, the nanoporous thinfilm can act as a diffusion barrier for a variety of bioactive agents.

In certain embodiments, the average pore size of the nanoporous thinfilm approaches the size of the bioactive agent solute (e.g., an proteintherapeutic), such that the bioactive agent molecules diffuse via singlefile diffusion (SFD) or hindered diffusion through the nanopores. Insuch cases, substantial deviations from Fick's laws may occur anddiffusion of the bioactive agent may occur independently of theconcentration gradient of bioactive agent.

In some embodiments, the nanoporous thin film includes a biodegradablepolymer as described above (e.g., PCL). In some embodiments, thenanoporous thin film has a thickness of about 10 μm or less, such asabout 8 μm or less, about 6 μm or less, about 4 μm or less, about 2 μmor less, or about 1 μm or less.

Multilayer Thin Film Structures

The subject devices may form any convenient structure, such as but notlimited to, a furled or an unfurled structure, a folded structure, atubular structure, a planar structure, a toric structure or a discoidstructure.

In some embodiments, the subject devices form either a furled or anunfurled structure. As used herein, the term “furled” refers to astructure of a material where the material is curled or rolled uponitself (e.g., the structure is an annular sheet disposed about a centralaxis) as compared to a substantially planar, flat or “unfurled”structure of the material. The term “furling” refers to the process oftransforming a material from an unfurled structure to a furled structure(e.g., whereby a flat sheet curls around a central axis to form anannular structure). The term “unfurling” refers to the reverse processwhere the thin film is unrolled, unfolded, or spread out. Application ofsuitable furling or unfurling conditions to a subject device can resultin transformation to produce a desired furled or unfurled structure,respectively. A multilayer thin film device structure of the presentdisclosure may spontaneously furl or unfurl in response to suitableconditions. For example, drying conditions sufficient to furl thesubject device and produce a furled structure. Alternatively, contact ofa furled multilayer thin film structure with a hydrating liquid (e.g.,vitreous fluid present in the eye of a subject), produces asubstantially planar unfurled structure. In some cases, uponadministration and contact with a hydrating liquid, the multilayer thinfilm medical device expands. By “expands” is meant that the thin filmbecomes larger in size or volume as a result of the surrounding liquidhydrating the film.

In certain embodiments, the furled structure is substantiallycylindrical, e.g., a structure where a planar film has curled uponitself to form a cylindrical shape as depicted in FIG. 7. In certainembodiments, the furled structure is substantially frusto-conical. Byfrusto-conical is meant a structure having the shape of a frustum of acone, i.e., the shape of a cone whose tip has been truncated by a planeparallel to its base.

In certain embodiments, the device has an unfurled structure thatincludes a substantially circular peripheral edge.

In some embodiments, the multilayer thin film devices are fabricated tohave a diameter of between about 1 mm and about 50 mm, such as betweenabout 1 mm and about 10 mm, between about 2 mm and about 8 mm, betweenabout 3 mm and about 7 mm, between about 4 mm and about 6 mm. In somecases, the diameter is about 1 mm, about 2 mm, about 3 mm, about 4 mm,about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm or about 10mm. In some embodiments, the multilayer thin film devices are fabricatedto have an area between about 1 mm² and about 100 mm², including betweenabout 4 mm² and about 64 mm², between about 9 mm² and about 49 mm²,between about 16 mm² and about 36 mm², such as about 16 mm², about 25mm², or about 36 mm².

In some embodiments, the multilayer thin film is fabricated to have athickness between about 1 μm and about 1 mm, such as between about 10 μmand about 500 μm, between about 50 μm and about 300 μm, between about100 μm and about 200 μm, such as about 100 μm, about 125 μm, about 150μm, about 175 μm or about 200 μm.

Methods of Preparation

Also provided are methods of preparing the subject multilayer thin filmmedical devices. In some embodiments, the method includes fabricating afirst thin film layer that includes a biodegradable or non-degradablepolymer and a pore forming agent; depositing a layer of bioactive agentover the first thin film layer; positioning a second thin film layer(e.g., a non-porous or porous layer) over the layer of bioactive agentto produce a multilayer thin film structure; sealing the bioactive agentbetween the first thin film layer and the second thin film layer, byusing an adhesive, or by using heat, or a solvent to melt the layers;and forming a furled structure of the multilayer thin film device bydrying the multilayer thin film structure for a sufficient period oftime or by mechanically rolling the device. In some embodiments, asingle film may be sealed to itself around a bioactive reservoir tocreate a single film multilayer device.

The thin film layers may be fabricated using any convenient method. Forexample, the first thin film layer that includes a biodegradable ornon-biodegradable polymer and a pore forming agent, as described above,may be fabricated by spin-casting a solution of biodegradable polymer(e.g., PCL) and pore forming agent (e.g., gelatin) onto a flat circularmold using methods readily adapted from those described by Steedman etal. (“Enhanced differentiation of retinal progenitor cells usingmicrofabricated topographical cues. Biomedical Microdevices”, 12(3)(2010) 363-369). The second non-porous thin film layer may be fabricatedusing similar methods to those described above. Devices with non-porousfirst thin film layers may be fabricated using similar methods to thosedescribed above.

A reservoir of bioactive agent may be prepared in the subject multilayerthin films, e.g., as a discrete layer of a composition that includes thebioactive agent. The layer of bioactive agent may be prepared using anyconvenient method. For example the bioactive agent may be deposited as alyophilized composition. For example, the layer of bioactive agent maybe formed by application to a thin film of a solution that includes thebioactive agent followed by subsequent drying (e.g., evaporation,lyophilization). The layer of bioactive agent is positioned between thefirst and second thin film layers.

In certain embodiments, the sealing step of the subject methods isperformed using an annulus that may be heated. An exemplary heating stepincludes the use of an annulus (e.g., a PDMS annulus heated) that isheated to a temperature (e.g., 80° C.) above the melting temperature ofthe polymers (e.g., PCL) used in the fabrication of the thin filmlayers. Application of the heated annulus to one surface of themultilayer thin films (e.g., by pressing down on the annulus with a flatstainless steel weight for 30 seconds) melts and seals the filmstogether to produce a multilayer thin film structure having a annularcircumference. The size and shape of the annulus may be selected toproduce devices of a desired size. In such cases, the first thin filmlayer and the second thin film layer are bonded thereby sealing thebioactive agent between the multilayer thin film structure.

In certain embodiments, the sealing step of the subject methods isperformed using a laser beam to heat a defined area of the thin filmlayers, for example, a circular area surrounding the area where thebioactive agent has been disposed. In certain embodiments, the sealingstep of the subject methods is performed by disposing an adhesivematerial on one or both of the thin film layers. For example, anadhesive material may be disposed on the first thin film layer and/orthe second thin film layer in an area surrounding the area where thebioactive agent is disposed. The adhesive may seal the two layers whenthe two layers are brought in contact. Alternatively, the adhesive maybe a heat sensitive adhesive or a pressure sensitive adhesive. In theseembodiments, heat or pressure may be applied in order to seal the layersof the thin film device.

In some embodiments, forming a furled multilayer thin film device may beperformed by drying the multilayer thin film device, for example, underconditions sufficient to allow the multilayer thin film structure toform a furled structure. Exemplary drying conditions includelyophilizing conditions under reduced pressure, where most of the waterpresent may be evaporated from the multilayer thin film device while thestability and bioactivity of the bioactive agent is maintained. In otherembodiments, forming a furled multilayer thin film device may beperformed by mechanically rolling the multilayer thin film device into afurled structure.

In some embodiments, the method of preparing the subject device is amethod that includes fabricating a first nanoporous thin film layer overa nanotemplate; fabricating a second thin film layer comprising abiodegradable polymer and a pore forming agent over the first nanoporousthin film layer; removing the first and second thin film layers from thenanotemplate; fabricating a third non-porous thin film layer comprisinga plurality of reservoir wells; depositing a bioactive agent in theplurality of reservoir wells; positioning the third non-porous thin filmlayer over the first and second layers to produce a multilayer thin filmstructure; sealing the multilayer thin film structure to bond the firstthin film layer to the third thin film layer thereby sealing thebioactive agent between the multilayer thin film structure; and furlingthe multilayer thin film device by, for example, drying the multilayerthin film device for a sufficient period of time to allow the multilayerthin film structure to form a furled structure, or by rolling themultilayer thin film device, such as mechanically rolling.

The subject method may be performed using methods similar to thosedescribed above. The first nanoporous thin film layer may be fabricatedby any convenient method. For example, a nanotemplate synthesis methodmay be used to produce nanostructures in a biodegradable polymer thinfilms that are readily adapted for use in the subject methods ofpreparation. An inorganic nanotemplate of aligned and ordered nanowires(e.g., ZnO rods) may be prepared using any convenient method. A varietyof techniques may be used to deposit a polymer (e.g., a biodegradablepolymer) onto the nanotemplate. For example, the polymer can be heatedabove its melting point and allowed to conform to the template. Forexample, spin casting of polymer solutions may be used. In some cases,to provide mechanical robustness, prior to template removal, a secondthin film layer (e.g., a microporous thin film layer, or a layer thatincludes a pore forming agent) is fabricated on top of the firstnanoporous thin film layer. In some embodiments, the thickness of thenanoporous thin film layer corresponds to the lengths of the nanorods ofthe template.

A reservoir of one or more bioactive agents may be incorporated into themultilayer thin film before administration to a subject, using anyconvenient method. For example, by depositing a lyophilized material ona thin film, or by dipping the device during fabrication into a solutionor dispersion containing the agent. In some embodiments, a compositionthat includes the bioactive agent is deposited on a thin film thatincludes a plurality of structures, as described above. The compositionfills the structural voids defined by these structures (e.g., wellsacross on surface of a non-porous thin film as depicted in FIG. 10A).The reservoir of bioactive agent may then be positioned between thefirst and second thin film layers, and the multilayer thin filmstructure subsequently sealed and furled, as described above.

Methods of Local Delivery of Bioactive Agent

Also provided is a method of localized delivery of a bioactive agent toa tissue. In some embodiments, the method includes administering to asubject a multilayer thin film medical device, as described above. Byadministering is meant positioning the device at a location in the bodyof a subject. Positioning the device in a subject may be carried out byplacing the device (e.g., placing surgically, injection by syringe ordelivery by catheter, placing orally in mouth) in any suitable opening,tissue, or body cavity of the subject where local delivery of thebioactive agent is desired. For example, the device may be injected in acavity of the eye of the subject, such as the peripheral vitreous cavityof the eye. For example, the device may be positioned in any convenientspace in a tissue mass. The device may have a furled structure suitablefor injecting, e.g., injection by syringe.

When a furled multilayer thin film device is positioned in the subjectit may contact a hydrating liquid in the subject and unfurl to producean unfurled multilayer thin film structure. In addition, the hydratingliquid may dissolve the pore forming agent from a layer of the unfurledmultilayer thin film structure to produce a porous layer that providesfor release of the bioactive agent from the medical device.

In some embodiments, the subject device releases the bioactive agent ina time-controlled fashion. In this way, the therapeutic advantagesimparted by the addition of the bioactive agent may be continued for anextended period of time. In some embodiments, the subject device willelute the bioactive agent to the surrounding tissue upon placement ofthe device in the patient for a period ranging from about 2 minutes toabout 1 day or more, such as 2 days or more, 3 days or more, 7 days ormore, 14 days or more, 21 days or more, or 1 month or more. In certainembodiments of the subject method, the releasing device locally deliversan effective amount of the bioactive agent over an extended period oftime, e.g., 1 or more months, such as 2 or more, 3 or more, 4 or more, 5or more, 6 or more, 9 or more or 12 or more months.

In certain embodiments of the subject method, the releasing of thebioactive agent from the medical device is a controlled release thatoccurs without an initial burst of bioactive agent. By “without aninitial burst” is meant that the bioactive agent does not release fromthe device in an appreciable amount during a predetermined initialperiod (e.g., 1 week or less, such as 3 days or less, 1 day or less, 12hours or less, 6 hours or less, 3 hours or less or 1 hour or less). Thepresence and level of an initial burst of a bioactive agent may bereadily determined by one of ordinary skill in the art employing anyconvenient pharmacological methods. For example, less than about 50% ofthe bioactive agent is released in the predetermined initial period,such less than about 40%, less than about 30%, less than about 20%, lessthan about 10%, less than about 5%, less than about 2%, or less thanabout 1% of the bioactive agent.

In certain embodiments of the subject method, the releasing of thebioactive agent from the medical device is substantially zero order overan extended period of time. By “substantially zero order” is meant arelease profile of the bioactive agent from the device that provides fora substantially constant release of drug, e.g., a release profile wherethe fraction of bioactive agent eluted from the device is substantiallylinear with respect to time, over an extended period of time. Forexample, a release profile where about 20% or less, such as about 10% orless, or 5% or less of bioactive agent is released after 10 daysfollowing administration. For example, a release profile where about 40%or less, such as about 20% or less, or about 10% or less of bioactiveagent is released after 20 days following administration. For example, arelease profile where about 60% or less, such as about 30% or less, orabout 15% or less of bioactive agent is released after 30 days followingadministration. For example, a release profile where about 80% or less,such as about 40% or less, or about 20% or less of bioactive agent isreleased after 40 days following administration. For example, a releaseprofile where about 80% or less, such as about 70% or less, about 60% orless, or about 50% or less of bioactive agent is released after 50 daysfollowing administration. For example, a release profile where about 90%or less, such as about 80% or less, about 70% or less, about 60% orless, or about 50% or less of bioactive agent is released after 60 daysfollowing administration. For example, a substantially zero orderrelease profile of a bioactive agent that is a protein, where theprotein is released from the device at a rate of about 20microgram/month to about 1.0 mg/month over an extended period of time.For example, a substantially constant release of an effective amount ofa protein bioactive agent (e.g., interferon) at about 0.5 mg/day over anextended period of time.

The bioactivity or stability of the bioactive agent may be maintained inthe device after administration for an extended period of time. Forexample, the bioactivity of a bioactive agent (e.g., an antibodytherapeutic) per unit amount of the agent that is eluted from the deviceis substantially constant over an extended period of time, e.g., 1 monthor more, 2 months or more, 70 days or more, 3 months or more, 6 monthsor more, or 1 year or more. Accordingly, the subject devices provide fora significant improvement in maintaining the bioactivity of a bioactiveagent over an extended period of time, e.g., 1 month or more, 2 monthsor more, 70 days or more, or 3 months or more, 6 months or more, or 1year or more as compared to the bioactivity of the bioactive agent thatis similarly positioned in a subject but not present in the multilayerthin film device.

In certain embodiments of the subject method, the device is administeredintravitreally in the eye(s) of a subject, for example, the device isadministered by intravitreal injection. In other embodiments, the deviceis administered subretinally to a subject. In other embodiments,administering the subject device to the eye of a patient includeadministration to one or more of the anterior chamber, vitreous,suprachoroidal space, sub-conjunctival space of the eye(s) of a patient.In certain embodiments, the bioactive agent is a protein therapeutic,such as an anti-VEGF antibody. In certain embodiments, the hydratingliquid in the subject is vitreous fluid.

In certain embodiments of the subject method, the insertion is in theanterior chamber of the eye. In certain embodiments, the bioactive agentis a small molecule therapeutic, such as latanoprost for glaucomatreatment.

In certain embodiments of the subject methods, the multilayer thin filmmedical device further comprises a third nanostructured porous layerpositioned between the first layer and the reservoir of the bioactiveagent, wherein the third nanostructured porous layer includes abiodegradable polymer (e.g., PCL). In certain embodiments, the thirdnanostructured porous layer has an average pore size of between about 2nm and about 50 nm.

In certain embodiments of the subject method, the second non-porouslayer is biodegradable. In certain embodiments, the second non-porouslayer includes PCL.

Also provided is a method of treating a patient in need of a medicaldevice for drug delivery comprising the steps of selecting the medicaldevice. Exemplary devices include, cardiovascular devices, neurologicaldevices, neurovascular devices, gastrointestinal devices, musculardevices, ocular devices, and the like. In this embodiment, the term“selecting” means, for example, purchasing, choosing, or providing thedevice rather than preparing the device.

The methods and devices disclosed herein can be used for both humanclinical medicine and veterinary applications. Thus, the subject orpatient to whom the device is administered can be a human or, in thecase of veterinary applications, can be a laboratory, agricultural,domestic, or wild animal. The subject devices and methods can be appliedto animals including, but not limited to, humans, laboratory animalssuch as monkeys and chimpanzees, domestic animals such as dogs and cats,agricultural animals such as cows, horses, pigs, sheep, goats, and wildanimals in captivity such as bears, pandas, lions, tigers, leopards,elephants, zebras, giraffes, gorillas, dolphins, and whales.

In some embodiments, the release kinetics of the one or more bioactiveagents that are eluted from the subject devices provide for asubstantially constant local delivery of a therapeutically relevantdosage of the bioactive agent. In certain embodiments, the releasekinetics of the bioactive agent is substantially zero order over anextended period of time. In some embodiments, a composition of thesubject device may be designed to provide for two elution profiles,e.g., a first early elution of bioactive agent from a first layer, and asecond later elution of bioactive agent from a second layer. In someembodiments, the bioactive agent is stable in the subject devices overan extended period of time. In certain embodiments, the activity of thebioactive agent in the reservoir is maintained following administrationin vivo. For example, the activity of the bioactive agent in thereservoir is maintained over a period of about 30 or more days, such asabout 60 or more days, 70 or more days, 3 or more months, about 4 ormore months, about 5 or more months, about 6 or more months, about 8 ormore months, about 10 or more months, or about 12 or more months.

Kits

Kits for use in connection with the subject devices and methods are alsoprovided. The above-described multilayer thin film devices, comprisingone or more bioactive agents for elution to the surrounding tissue uponplacement in a subject, can be provided in kits, with suitableinstructions in order to conduct the methods as described above. Incertain embodiments, the kit contains a subject device that has a furledstructure. In some embodiments, the device has an unfurled structure andthe kit includes instructions for furling the device so that the devicemay be positioned in a subject by syringe.

The subject kits may also include a syringe capable of delivering thedevice to a subject, e.g., by injection of a carrier fluid containingthe device having a furled structure. The syringe has a gauge (e.g., 20gauge) suitable for in vivo injection of the device. In someembodiments, the syringe is pre-loaded with a carrier fluid thatcontains the device, where the device is maintained in a furledstructure in the carrier fluid. In other embodiments, the kit includes acontainer for storing the device prior to loading of the syringe andadministration to the subject, where the device can be stored having afurled or an unfurled structure. In certain embodiments, when the deviceis stored in the container in an unfurled state, the kit may includeinstructions for furling the device prior to administration, e.g., bydrying under reduced vacuum. The container may optionally include acarrier fluid suitable for storing the subject device and/oradministration of the device.

In some embodiments, the kit contains in separate containers materialsnecessary for fabricating the multilayer thin film. The kit may alsoinclude materials for administering the device to a subject.Instructions (e.g., written, tape, VCR, CD-ROM, etc.) for carrying outthe methods may be included in the kit. The kit can also contain,depending on the particular method, other packaged reagents andmaterials (i.e. buffers and the like). The instructions are generallyrecorded on a suitable recording medium. For example, the instructionsmay be printed on a substrate, such as paper or plastic, etc. As such,the instructions may be present in the kits as a package insert, in thelabeling of the container of the kit or components thereof (e.g.,associated with the packaging or subpackaging), etc. In otherembodiments, the instructions are present as an electronic storage datafile present on a suitable computer readable storage medium, e.g.,CD-ROM, diskette, etc, including the same medium on which the program ispresented.

In yet other embodiments, the instructions are not themselves present inthe kit, but means for obtaining the instructions from a remote source,e.g. via the Internet, are provided. An example of this embodiment is akit that includes a web address where the instructions can be viewedfrom or from where the instructions can be downloaded.

Still further, the kit may be one in which the instructions are obtainedare downloaded from a remote source, as in the Internet or world wideweb. Some form of access security or identification protocol may be usedto limit access to those entitled to use the subject kits. As with theinstructions, the means for obtaining the instructions and/orprogramming is generally recorded on a suitable recording medium.

EXAMPLES

The following examples are put forth so as to provide those of ordinaryskill in the art with a complete disclosure and description of how tomake and use embodiments of the present disclosure, and are not intendedto limit the scope of what the inventors regard as their invention norare they intended to represent that the experiments below are all or theonly experiments performed. Efforts have been made to ensure accuracywith respect to numbers used (e.g. amounts, temperature, etc.) but someexperimental errors and deviations should be accounted for. Unlessindicated otherwise, parts are parts by weight, molecular weight isweight average molecular weight, temperature is in degrees Centigrade,and pressure is at or near atmospheric.

Methods and Materials

The following methods and materials were used in the Examples below.

Microporous Thin Film Fabrication

Thin films were spin-cast onto a flat circular poly(dimethylsiloxane)(PDMS) (Sylgard 184, Dow Corning, Midland, Mich.) mold due to itsflexibility and the delicacy of the PCL/gelatin thin films. To fabricatethe PDMS mold, the base and curing agent were mixed at a 10:1 ratio,degassed under vacuum, poured onto a 3″ Silicon wafer, and baked at 65°C. for 2 hours. Once cured, the PDMS was peeled from the silicon masterand cut into a 35 mm diameter circle. Separate solutions ofpolycaprolactone (PCL) (MW 80,000, Sigma-Aldrich, St. Louis, Mo.) andgelatin (from porcine skin, Sigma-Aldrich) were constantly stirred in0.1 g mL⁻¹ 2,2,2-trifluoroethanol (TFE) (Sigma-Aldrich) on a hot plateat 80° C. until dissolved. PCL and gelatin solutions were then combinedinto centrifuge tubes in the following volumetric ratios: 7:3, 8:2, 9:1,and 10:0 (PCL:Gelatin). To mix the PCL and gelatin together, solutionswere vortexed for 30 seconds and inverted twice. This process wasrepeated for at least 5 minutes per solution immediately prior tocasting. PCL/gelatin solutions were spin cast using a P6700 SeriesSpincoater (Specialty Coating Systems, Indianapolis, Ind.) at 1500 RPMfor 1 minute as previously described [Steedman et al., “Enhanceddifferentiation of retinal progenitor cells using microfabricatedtopographical cues.” Biomedical Microdevices 12(3) (2010) 363-369]. Thinfilms were carefully peeled from the PDMS mold after spin casting usingforceps.

Nanoporous Thin Film Fabrication

All chemicals for nanoporous PCL fabrication were obtained fromSigma-Aldrich (St. Louis, Mo.). Nanoporous PCL films were fabricatedusing zinc oxide nanorod templates using techniques. Zinc oxide rodswere grown on glass or silicon substrates that were cleaned prior to usewith a solution of sulfuric acid and hydrogen peroxide (3:1) for 30minutes and subsequently rinsed with deionized water and dried withnitrogen. Substrates were exposed to an oxygen plasma (200 W, 0.5 mTorr)for 5 minutes prior to spin casting a zinc acetate (ZnAc₂) seed layer.For this, a solution of 0.75 M ZnAc₂ and ethanolamine in2-methoxyethanol was cast onto clean glass or silicon substrates at 1000rpm for 60 seconds. Substrates were annealed on a hot plate at 400° C.for 30 minutes to convert ZnAc₂ into ZnO. Substrates were then placed inan aqueous 5 mM ZnAc₂ solution at 85-90° C. for 4 hours (replacing thegrowth bath once), which resulted in the growth of ZnO nanorods. A 300mg/ml solution of PCL in 2,2,2-trifluoroethanol was prepared asdescribed above and cast onto ZnO templates at 500 rpm for 30 secondsfollowed by 1500 rpm for 30 seconds, which is sufficiently thick tocover the ZnO template. These substrates were heated to 130° C. on a hotplate to remove any excess solvent and to allow the PCL to intimatelycontact the template. ZnO templates were then etched with 10 mM H₂SO₄until the template was removed and PCL films naturally floated off.

Thin Film Degradation Analysis

Thin films were stored in PBS under constant agitation for 5 days. Priorto imaging, samples were rinsed with deionized water and dehydrated in avacuum oven. Samples were imaged using a mySEM scanning electronmicroscope (NovelX, Lafayette, Calif.) with an accelerating voltage of 1kV. For pore area and porosity calculations, 3 thin films of eachPCL:Gelatin ratio were imaged. For each thin film, 10 random areas perthin film were imaged and compiled. Pore areas were calculated usingImageJ (National Institutes of Health, Bethesda, Md.).

Multilayered Thin Film Device Fabrication

Devices were fabricated from two thin films, a non-porous PCL base layerand a microporous 9:1 PCL/gelatin top layer as illustrated in FIG. 3.PCL base layers were fabricated using a concentrated solution of PCL(0.2 g mL⁻¹ in TFE), which were spin cast at 1500 RPM for 2 minutes ontoa silicon wafer. Lyophilized protein (1-4 mg) was placed in between thetwo device layers and secured on a silicon wafer. An annulus-shapedpiece of PDMS was heated to 80° C. then placed on top of the two thinfilms. A flat stainless steel weight (170 g) was used to press down onthe PDMS annulus for 30 seconds, melting and sealing the two filmstogether. The small flat weight was used to ensure uniform sealing.Elution of BSA and IgG from thin film devices was monitored for 10 weeksand compared to elution from non-porous PCL-only devices. Three devicesof each type were fabricated and analyzed per experiment.

Profilometry

Device thickness was characterized with an Ambios Technology XP-2 StylusProfiler (Santa Cruz, Calif.). Profilometry was conducted with a scanspeed of 0.01 mm sec⁻¹, a length of 1.5 mm and a stylus force of 0.2 mg.

Micro Bicinchoninic Acid Assay

A micro bicinchoninic acid assay (Thermo Scientific Pierce, Rockford,Ill.) was performed to quantify protein elution from PCL thin filmdevices. Multilayered thin films loaded with lyophilized BSA(Sigma-Aldrich) or IgG (isolated from bovine serum, Sigma-Aldrich) wereplaced in 5 mL of PBS in centrifuge tubes and shaken continuously atroom temperature for 10 weeks. 1 mL of solution was removed duringsampling and replaced with fresh PBS. Samples were read at 562 nm on aSpectraMax 190 microplate reader (Molecular Devices, Sunnyvale, Calif.).Data and linear regression analysis were performed in Excel (Microsoft,Redmond, Wash.).

Bovine IgG Enzyme Linked Immunosorbent Assay (ELISA)

A bovine IgG enzyme linked immunosorbent assay (ELISA) (BethylLaboratories, Inc., Montgomery, Tex.) was performed to verify theactivity of eluted IgG from PCL/gelatin devices. Total protein sampleconcentrations were first determined with a micro bicinchoninic acidassay, and then diluted 1/100 to fall within the dynamic range of theELISA assay. These samples were then assayed, and the resultingconcentration values were compared to the previous bicichoninic acidassay results. A ratio of the two concentration values was calculatedover four time points between 1 and 70 days after device construction.

Rapamycin Loaded PCL Film

Rapamycin loaded PCL film was prepared by stirring a solution of 200mg/mL PCL in 2,2,2-trifluoroethanol (TFE) (Sigma-Aldrich) on a hot plateat 70° C. until dissolved. Rapamycin was then added to the solution at aconcentration of 5 mg/mL and stirred until dissolved. The solution wasthen spin-cast onto a 3 inch silicon wafer at 1000 rpm for 30 secondsfollowed by 2000 rpm for 30 seconds. Circular sections of the film 16 mmin diameter were cut and incubated in PBS at 37 C. To sample drugrelease, 1 mL of solution was removed during sampling and replaced withfresh PBS. Rapamycin concentration was read at 260 nm on a SpectraMax190 microplate reader (Molecular Devices, Sunnyvale, Calif.). Data andlinear regression analysis were performed in Excel (Microsoft, Redmond,Wash.).

Example 1

Microporous Thin Film Fabrication and Degradation

Solutions of PCL and gelatin were combined, respectively, in thefollowing volumetric ratios: 7:3, 8:2, 9:1 and 10:0. After vigorousmixing, the combined solutions were spin cast into flexible polymer thinfilms. Initially non-porous, thin films were exposed to PBS for 5 daysto eliminate the readily soluble gelatin components of the thin films.After 5 days of degradation in PBS, thin films were imaged usingscanning electron microscopy (FIG. 1). Micropores were found in all thinfilms containing gelatin, while PCL-only thin films showed no signs ofdegradation or porous architecture. Individual pore areas werequantified and are displayed in FIG. 1.

FIGS. 1A-F show images of scanning electron micrographs andcorresponding pore size histograms of PCL/gelatin thin films after fivedays of degradation in PBS. Thin films were made from mixtures of PCLand gelatin at ratios of 7:3 (A and B), 8:2 (C and D), and 9:1 (E andF). Thin films made from PCL only did not contain any pores.

Thin films fabricated with the highest concentration of gelatin (7:3)contained a broad range of pore sizes, the smallest less than 2 μm indiameter and the largest over 30 μm in diameter (FIGS. 1A and 1B). Thinfilms with a medium gelatin concentration (8:2) also contained a widerange of pore sizes, although the largest pores found in these filmswere smaller than in the 7:3 gelatin thin films and only reached amaximum of 28 μm in diameter (FIGS. 1C and 1D). Thin films with thelowest gelatin concentration (9:1) contained much smaller pores, 95% ofwhich were smaller than 10 μm in diameter (FIGS. 1E and 1F). Thin filmsfabricated without gelatin (10:0) were non-porous throughout the entirespin cast thin film surface.

The percent porosity, or the pore area divided by the total area of eachthin film was quantified and is shown in FIG. 2A. As the gelatin rapidlydissolves in PBS, increasing the amount of gelatin in the thin films ledto more porosity after degradation. The 7:3 films were the most porous,followed by the 8:2 films, and then by the 9:1 films. Since the 10:0films contained no gelatin, no degradation and therefore no porosity wasobserved.

FIGS. 2A-B illustrate the porosity and mass loss of PCL/gelatin thinfilms after incubation in PBS. A: Percent porosity of PCL/gelatin thinfilms of varying gelatin concentrations after 5 days in PBS. Overallporosity increases with gelatin concentration. B: Porosity resultingfrom gelatin dissolution lead to a decrease in mass. PCL swelling andsalt absorption leads to a small overall increase in mass for thin filmscontaining no gelatin. *p<0.05, Student-Newman, Keuls test. Error barsindicate standard deviation over three independent experiments.

The porosity found in the thin films is due to the incomplete mixing ofPCL and gelatin. Although both species dissolve in TFE, combining thetwo solutions results in a heterogeneous emulsion that must beconstantly mixed or the two solutions will separate into two immiscibleliquids. Due to the high viscosity of the dissolved solutions it wasempirically determined that maintenance of a consistent mixturenecessitated near constant vortexing prior to spin casting. Addingincreasing amounts of gelatin resulted in aggregation of the gelatin inthe PCL/gelatin mixture that was not found in the 9:1 thin films.

Degradation was also quantified using the amount of mass lost after 5days in PBS. Initial mass was determined prior to PBS immersion, whilepost-degradation mass was determined after 5 days in PBS and subsequentdehydration of the thin films in a vacuum oven. Results were consistentwith pore area and percent porosity; the 7:3 thin films lost the mostmass, approximately 25% of their initial mass, while 8:2 films lost justless than 10% on average. 9:1 thin films lost less than 5%, and filmscontaining no gelatin gained a very small amount of mass due to theimmersion in PBS (FIG. 2B). This most likely occurred due to water andsalt absorption, causing the PCL areas to swell during immersion in PBS.

Multilayered Thin Film Device Fabrication and Drug Elution PCL thin filmdevices were constructed from a PCL base layer and a microporous 9:1PCL/gelatin top layer as diagramed in FIG. 3. To restrict proteinelution by minimizing the porosity of the device, only 9:1 PCL/gelatinthin films were used to make the microporous top layer for allprotein-loaded experimental devices. Lyophilized protein was depositedbetween the two thin film layers, which were then melted together usinga PDMS annulus. Devices were immersed in PBS at room temperature, andelutions of BSA and IgG from the PCL/gelatin thin film devices werequantified over a 10-week period. Non-porous devices made from twoPCL-only thin films were also constructed and used as controls.

FIGS. 3A-C illustrate the fabrication of the multilayered polymer thinfilm device. A: Lyophilized protein was contained between a non-porousPCL thin film base layer and a microporous PCL/gelatin thin film. B: Afinished device ˜2 mm in diameter. C: Profile of the PCL/Gelatin Deviceedge.

BSA elution from porous PCL/gelatin thin film devices and non-porousPCL-only thin film devices is presented in FIG. 4A. BSA eluted from thePCL/gelatin devices with zero-order kinetics for the first seven weeks,corresponding to slightly more than 60% of the ˜3 mg BSA loaded intoeach device. Similarly, IgG elution is presented in FIG. 4B. Zero-orderelution from the 9:1 PCL/gelatin devices was also achieved with IgG forthe first seven weeks.

FIGS. 4A-B show the elution of protein from a PCL/gelatin thin filmdevice. A: Fractional elution of BSA from 9:1 PCL/gelatin and PCL-onlythin film devices. Zero-order elution was observed for the first 7 weeksin PCL/gelatin devices, after which device failure led to a burstrelease phase. PCL-only devices began to leak after 8 weeks. B:Fractional elution of IgG from 9:1 PCL/gelatin thin film devices.Zero-order elution of IgG from PCL/gelatin devices was observed fornearly all 10 weeks. Error bars indicate standard deviation over threeindependent experiments.

Protein elution from one BSA-loaded and one IgG-loaded PCL/gelatin thinfilm device is directly compared in FIG. 5. Elution for 7 weeks aredisplayed, corresponding to zero-order release kinetics with R² valuesof 0.99 and 0.94 for BSA and IgG, respectively. BSA eluted at a rate of36 μg/day, while IgG eluted at a slower rate of 20 μg/day. IgG's slowerelution rate is most likely due to its larger molecular weight (150 kDaversus 66 kDa for BSA).

FIG. 5 shows a comparison of the rates of elution of BSA and IgG from aPCL/gelatin thin film device. Larger molecular weight IgG (150 kDa)eluted at a slower rate than BSA (66 kDa). Linear regression analysisgave elution rates of 0.36 μg/day for BSA (R²=0.99) and 0.20 μg/day forIgG (R²=0.94).

IgG concentration was quantified using two different assays to verifyprotein activity throughout the course of the experiment. FIG. 6A showsa comparison of the ratio of eluted IgG concentrations determined byELISA and BCA assays. Concentrations were compared at 1, 28, 56, and 70days of elution. Error bars indicate standard deviation over threeindependent experiments. The ratio of these two concentrations isplotted for four time points from 1 to 70 days of elution. The BCA assayquantifies total protein concentration, while the ELISA is much morespecific and only quantifies bound IgG. A ratio of 1 represents an equalconcentration of IgG between both assays, demonstrating that the IgGreleased from PCL/gelatin thin film devices is active after 70 days ofelution. As the differences between the four data points are notsignificant and the standard deviations all fall within a ratio of 1these results show that the IgG did not degrade over the course of theexperiment.

FIG. 6B shows the activity of IgG eluted into the eye afteradministration of IgG containing thin film device. In vivo activity ofIgG was detectable in the eye 6 weeks-post administration.

Example 2

Nanostructured Thin Films

A template-synthesis method is used to produce nanostructures in thinbiodegradable polymer films. This approach is based on templating whichentails using an inorganic nanostructured surface (e.g.,well-characterized rods structures of a zinc oxide ZnO material) as atemplate for the subsequent creation of a “soft” biopolymer thin filmwith desired nano-architectures. A two-step procedure is used for ZnOnanrod growth: a nanostructured seed layer is deposited and rods aregrown hydrothermally from the seed layer. Through variations is seedlayer deposition and hydrothermal growth condition, a variety ofmorphologies are produced, from random to well-oriented rods. Control ofprocessing conditions allows nanorods to be fabricated in a wide rangeof diameters, lengths and inter-rod spacing.

A variety of techniques are used to deposit the target polymer onto ZnOtemplates.

In one example, polymers are heated above their melting point andallowed to conform to the template. Alternatively, spin casting ofpolymer solutions is used to generate thin films with reproduciblethickness. Polycaprolactone was selected as a starting material since ithas shown excellent biocompatibility and integrity within the eye. Underphysiological conditions, PCL degrades by random chain scission, whichgives rise to a two-phase degradation. Initially, as molecular weightdecreases the physical structure is unaffected since generated polymerchains are not sufficiently soluble, but after extended degradation,there is an increased generation of monomeric degradation products,resulting in significant physical degradation.

80 kDa PCL films do not degrade until after 1 year in the eye and basedon the approximate MW for macroscopic degradation (8 kDa), it isestimated that PCL devices of MW between 15 and 20 kDa will start tostructurally breakdown after 4 months and lose mechanical integrity by 6months. Therefore, films are created using two exemplary differentratios (20:80 and 45:55) of 80 kDa:10 kDa PCL (T_(m)=58-63° C.,T_(g)=−65 to −60° C.). We can also incorporate other degradable polymer.In addition, other films may be created, such as co-polymers of 25/75poly(DL-lactide-co-ε-caprolactone) (25/75 DLPLCL) (amorphous, T_(g)=20°C.) or 80/20 poly(DL-lactide-co-ε-caprolactone) (80/20 DLPLCL)(amorphous, T_(g)=20° C.) to modulate the degradation rate. Finally, ZnOtemplates are then removed by dissolution in either acidic or stronglybasic solutions. The template structure is inverted upon transfer andthe subsequent polymer thin film exhibits nano-channels for drug elutionand controlled release. Using this approach, ZnO rods with average roddiameter of 23±7 nm and density of approximately 10¹⁰ rods/cm² canresult in a PCL film with pore sizes of 21±7 nm and a pore density of5×10⁹ pores/cm². The thickness of the film corresponds to the lengths ofthe nanorods that are grown, e.g., about 1 micron. Therefore, to furtherimprove mechanical robustness, an additional porous layer is depositedprior to template removal, resulting in films with both nanoporous andmicroporous regions (FIGS. 9A-9C). For example, this is accomplished bycasting a polymer mixture that naturally forms a porous network, such aspolyethyleneglycol (PEG) and PCL, where PEG is easily dissolved inconjunction with template removal.

An exemplary process for thin film fabrication is illustrated in FIGS.8A-8E. (FIG. 8A) A clean silicon substrate is (FIG. 8B) spin cast with azinc oxide seed layer and nanorods are hydrothermally grown. Onto theZnO template (FIG. 8C) PCL is spin cast followed by (FIG. 8D) spincasting a PCL and PEG solution. (FIG. 8E) rinsing with deionized waterrinses the PEG-phase from the supporting layer and 10 mM H₂SO₄ etchesthe ZnO template to leave a supported nanostructured PCL thin film. FIG.8F shows a scanning electron microscope image of a typicalnanostructured PCL film. FIG. 8G shows thin layer of nanostructures onsupporting membrane.

Scanning electron microscopy (SEM) is used to verify template morphologyand fidelity of transfer to the polymer film. Additionalcharacterization with electron dispersive x-ray spectroscopy (EDX) orx-ray photoelectron spectroscopy (XPS) is used to determine chemicalcomposition and demonstrate effective removal of the ZnO template.Nanostructured membranes are then heat sealed to an impermeable cappingfilm containing a drug reservoir (FIG. 10A).

As an example, using an inorganic template of aligned and orderednanowires produces a nanoporous polymer membrane, as described above, anexemplary thin film was made from 80 kDa MW polycaprolactone that iscurled up in its dry state and unfurls when in an aqueous environment(FIG. 7). This thin film device was fabricated to have both physicaldimensions (less than 100 microns) and mechanical properties(furlability) suitable for the minimally invasive drug deliveryapplication described herein.

Physical Properties of Thin Film Devices

Flexible soft materials were manipulated, with a particular focus onfurlability to allow minimally invasive insertion into target tissues. Apolycaprolactone thin film device, approximately 100 microns thick and 5by 5 mm, is able to hold sufficient drug for 6 month delivery ofanti-VEGF and still be delivered via standard injection. An extensiveevaluation of exemplary devices (same size and material composition butvarious molecular weights) was undertaken to determine their suitabilityfor intraocular administration Animal studies data indicated that a filmcomposition of 45/55 80 kDa:10 kD PCL is still intact at 5 monthswhereas 20/80 80 kDa:10 kD PCL shows signs of degradation at 2 months.Further tuning of the parameters would result in the optimization of thedegradation profile of the devices for zero-order release.

Drug Loading Approaches and Drug Payload

Because nanoporous film fabrication is independent of drug loading,several strategies are utilized to incorporate the therapeutic payload.One approach joins the membrane with an underlying film containinglarger drug reservoirs. This configuration allows for a large drugcarrying capacity and versatility in payload formulation, while thenanoporous membrane helps to control drug elution out of the reservoirstructure.

By utilizing a further microporous supporting layer, the nanochannelsare placed near the neutral mechanical plane of the device, minimizingstrain on the nanopores upon rolling/unfurling. Photo- and softlithographic techniques are used to fabricate a reservoir component ofthe device: photolithography is used to create a master mold on asilicon wafer by patterning a photocurable epoxy (SU-8), whichdetermines eventual reservoir geometry. A precise master pattern isdesigned using CAD, and patterned on a chromium mask, to act as astencil for optical patterning. Soft lithography is then used to castthe inverse of the master mold into an elastomer polydimethylsiloxane(PDMS). By casting the polymer of interest against the PDMS mold, thegeometry of drug loaded reservoirs is transferred directly to thedesired polymer, e.g., as shown in FIG. 10A. The entire device is flat,thin (e.g., about 100 or less μm), and contains multiple therapeuticreservoirs; this provides the drug payload while minimizing burstrelease of therapeutic upon local film rupture or failure.

The modular nature of the thin film devices allows for the reservoirs tobe filled during construction of the multi-laminar biopolymer device inmultiple ways. One approach is to fill the reservoir and associatednanochannels of assembled devices by submersion into a solution of drugthat is directly lyophilized within the device. A second approach usesdirect deposition of lyophilized drug onto the reservoir film andsubsequent lamination of the films, heat sealing the films to generatethe complete device. Lyophilized drug is deposited directly into devicereservoirs or is incorporated within a biodegradable polymer or gelmatrix. Drug loading and reservoir patterning is confirmed usingfluorescently-labeled (FITC) target drug and visualized with fluorescentmicroscopy (FIG. 10A).

Payload Calculations and Safety Consideration

The loading requirements for a device are analyzed based upon azero-order release profile that maintains concentration in the posteriorof the eye for at least a 4 month period. For example, based on a 5 mm×5mm thin-film with 20 nm pores, with a void space of 50% a maximal drugload in this device is 1.3 mg of lyophilized drug, with release rates ashigh 2 μg/day/mm² based on membrane experiments. Desired release ratesdepend on drug affinity, vitreous half-life, and target vitreousconcentration. Based on clinical dosing, a continuous delivery device isestimated to require 4 μg/day to sustain therapeutic concentrations of,e.g., ranibizumab (50 μg/eye sustained concentration) or 480 μg of totaldrug for an exemplary device. Complete dose dumping for a devicedesigned for delivery over 6 months would produce systemic drugconcentration of less than 3.4 ng/ml upon failure, which falls wellbelow the 11-27 ng/ml threshold thought to inhibit VEGF by 50%. Inaddition, a multi-chambered reservoir (FIG. 10) minimizes the risk thatthe entire drug payload could be inadvertently dumped. Based uponconservative estimates of Lucentis© half-life in the vitreous humor, adevice loaded with approximately 800 μg of drug is estimated to maintaintherapeutic levels for a 6 month or longer period.

Ocular Biocompatibility Studies

To assess the structural integrity and ocular tolerance of micro- andnanostructured biopolymers, in vivo safety studies were conducted inadult rabbit eyes. Devices fabricated from poly(caprolactone) (PCL) wereadministered into eyes of anesthetized New Zealand White rabbits (N=15)using standard microsurgical techniques. Needle injection (20 gauge) wasused to insert furled biopolymer films into the vitreous. Over follow-upperiods ranging from 1-6 months, regular ophthalmic examinations wereperformed (slit lamp, tonometry, and indirect ophthalmoscopy) forsurveillance of ocular tolerability. Histologic studies on enucleatedpost-mortem eyes were performed at intervals of days to months toevaluate any morphologic abnormalities or device/tissue reactions. PCLfilms were retrieved from eyes to be evaluated by scanning electronmicroscopy (SEM) to determine the durability and structural integrity ofdevices. The PCL films were tolerated and structurally stable uponadministration in the eye, in both the anterior chamber and vitreousloci. Results of the in vivo ophthalmological examinations showed noadverse signs of ocular tolerability with respect to inflammation,chronic infection, cataract, and ocular pressure. No migration of thedevice was observed after 6 months. Histological examination of thetissue revealed no cellular inflammation or morphologic abnormalities atocular sites, including the retina trabecular meshwork and the specificsites of anatomic residence of the devices following administration.Device/tissue responses such as fibrosis, gliosis, or hemorrhage werenot seen.

Multilayer Thin Film Device Fabrication Apparatus Exemplary apparatususable for fabricating multilayer thin film disclosed here areillustrated in FIGS. 11A-11C.

FIG. 11A. The thin film device may include a flat PCL film, a drugpellet, and a nanostructured PCL film sandwiched between supportingstructures using a press weight. The apparatus containing theconstituent device layers is placed on a hot plate to fuse the PCLfilms. Because the base support is an annulus, the center of the devicesexperiences considerably less heating.

FIG. 11B. From the bottom up, devices consist of a flat PCL film, a drugpellet, and a nanostructured PCL film sandwiched between supportingstructures using a press weight. The base of the apparatus contains aresistive heating element that seals the device from the edge in. Bycontrolling power supplied to the heating element and duration ofheating, sealing can be controlled.

FIG. 11C. From the bottom up, devices consist of a flat PCL film, a drugpellet, and a nanostructured PCL film sandwiched between supportingstructures using a press weight. The base of the apparatus contains aresistive heating element that seals the device from the edge in. Thecenter in the base and top supports are removed to minimize heating tothe central portion of the device. By controlling power supplied to theheating element and duration of heating, sealing can be controlled.

Multilayer Thin Film Device for Controlled Release of Protein

Multilayer thin film devices having pore sizes in the range of 20 mn-40nm were fabricated as described herein.

FIG. 12 shows that FITC-BSA protein was released from nanostructured PCLdevices (n=3) with pore size of 20-40 nm at a release rate of 1 μg/dayover a time period of 210 days.

Multilayer Thin Film Device for Controlled Release of Small Molecules

A nanoporous multilayer thin film device was fabricated with a bioactivedrug reservoir containing the small molecule, rapamycin (MW 914 Da). Therelease kinetics of rapamycin from this nanoporous multilayer thin filmdevice was compared to the release kinetics of rapamycin from anon-porous device and from PCL thin film with rapamycin mixed in thepolymer film

FIG. 13 illustrates the release kinetics of a small molecule (Rapamycin,molecular weight 914.172 Da) from a nanoporous thin film device (solidcircles), non-porous device (solid squares) and from a PCL thin filmwith drug mixed in the polymer film (solid triangles).

The nanoporous thin film device consisted of a first layer of supportednanostructured film (nanostructured pores of 20-40 nm and support layerpores of 1-3 microns) and a second non-porous layer, produced asdescribed above. Rapamycin was placed on the second layer. with thenanoporous side of the first layer. The nanoporous first thin film layerwas placed on the non-porous film encapsulating rapamycin between thenanoporous layer and the non-porous layer.

The non-porous device included a first layer of a non-porous film.Rapamycin was deposited on a surface of the first layer. A secondnon-porous layer was placed on the first layer. The two non-porouslayers were sealed together encapsulating rapamycin between thenon-porous layer s.

For PCL thin film, the small molecule was mixed within the polymeritself rather than contained between two layers.

Kinetics of release of the small molecule drug rapamycin (sirolimus)from the nanoporous and non-porous PCL devices were compared to therelease kinetics of the same molecule from a PCL film containing thedrug. FIG. 13 illustrates that the nanoporous PCL device (nanostructuredpores of 20-40 nm and support layer pores of 1-3 microns) and thenon-porous PCL device provide for a zero order release of the smallmolecule over an extended period of time. In contrast, the PCL thin filmcontaining sirolimus releases small molecules over a shorter period oftime and with first order release kinetics.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity ofunderstanding, it is readily apparent to those of ordinary skill in theart in light of the teachings of this invention that certain changes andmodifications may be made thereto without departing from the spirit orscope of the appended claims.

Accordingly, the preceding merely illustrates the principles of theinvention. It will be appreciated that those skilled in the art will beable to devise various arrangements which, although not explicitlydescribed or shown herein, embody the principles of the invention andare included within its spirit and scope. Furthermore, all examples andconditional language recited herein are principally intended to aid thereader in understanding the principles of the invention and the conceptscontributed by the inventors to furthering the art, and are to beconstrued as being without limitation to such specifically recitedexamples and conditions. Moreover, all statements herein recitingprinciples, aspects, and embodiments of the invention as well asspecific examples thereof, are intended to encompass both structural andfunctional equivalents thereof. Additionally, it is intended that suchequivalents include both currently known equivalents and equivalentsdeveloped in the future, i.e., any elements developed that perform thesame function, regardless of structure. The scope of the presentinvention, therefore, is not intended to be limited to the exemplaryembodiments shown and described herein. Rather, the scope and spirit ofpresent invention is embodied by the appended claims.

What is claimed is:
 1. A method for providing a bioactive agent into aneye of a subject having an ocular condition, the method comprising:inserting into an eye of the subject a thin-film device comprising abioactive agent, the device comprising a biodegradable polymer layerenclosing the bioactive agent, wherein the bioactive agent is notpresent in the biodegradable polymer layer, wherein the device providesa zero-order release of the bioactive agent in the eye for a period ofat least 3 months, and wherein the biodegradable polymer layer is ananoporous layer comprising engineered nanopores, wherein the devicecomprises a microporous backing layer that supports the nanoporouslayer, wherein the bioactive agent is in contact with the nanoporouslayer.
 2. The method of claim 1, wherein the inserting comprisesinjecting the device via a needle containing the device in a lumenthereof.
 3. The method of claim 1, wherein the inserting comprisesinserting the device into the anterior chamber, vitreous, suprachoroidalspace, or sub-conjunctival space of the eye.
 4. The method of claim 1,wherein the inserting comprises inserting the device sub-retinally. 5.The method of claim 1, wherein the bioactive agent comprises a largemolecule.
 6. The method of claim 5, wherein the large molecule is aprotein or an aptamer.
 7. The method of claim 6, wherein the largemolecule comprises a protein, wherein the protein comprises an antibody.8. The method of claim 1, wherein the bioactive agent comprises a smallmolecule.
 9. The method of claim 1, wherein the ocular conditioncomprises uveitis, diabetic retinopathy, macular edema, glaucoma, orage-related macular degeneration (AMD).
 10. The method of claim 9,wherein the ocular condition comprises AMD and the bioactive agentcomprises an anti-VEGF antibody.
 11. The method of claim 9, wherein theocular condition comprises glaucoma and the bioactive agent is a smallmolecule.
 12. The method of claim 11, wherein the small moleculecomprises latanaprost, travarost, timolol, brimonidine or dorzolamide.13. The method of claim 1, wherein the biodegradable polymer layercomprises a poly(caprolactone) (PCL), a polymer blend comprising PCL, ora copolymer comprising PCL.
 14. The method of claim 1, wherein thedevice comprises a first bioactive agent and a second bioactive agent.15. The method of claim 1, wherein the device has a tubular structure, aplanar structure, a toric structure or a discoid structure.
 16. Themethod of claim 1, wherein the bioactive agent is lyophilized.